Air transmitter



Sept. 27, B. JONES AIR TRANSMITTER Filed DEC. l5, 1952 BY W? MM UnitedStates Patent K AIR TRANSMITTER Barton Jones, Los Angeles, Calif.

Application December 15, 1952, Serial No. 326,119

3 Claims. (Cl. 137-85) This invention relates to improvements in airtransmitters wherein it is `desired to transmit air pressure to areceiver at a pressure which is directlyproportional to the movement orposition of a movable element.

In air transmitters of this type that have heretofore been developed,air pressure issupplied to a relay at a constant or substantiallyconstant pressure. The relay serves to not only reduce the pressure anddeliver it to the outlet leading to the receiver, but in turn, iscontrolled by a pilot which is governed by the position of a movableelement. The pilot generally employed includes a nozzle through whichsome of the supplied air is discharged after passing through arestricter to reduce its pressure and a apper is engageable with thenozzle to control or modify the air that is discharged therethrough. Theflapper, in turn, is actuated by the movable element. In theconstructions heretofore employed, the pressure at which the airisrelayed or discharged throughthe nozzle is usually a direct function ofthe air pressure that is relayed by the relay to the receiver so that ifthe pressure that is released to the receiver is relatively high, thepressure at which the air is supplied to the nozzle is likewise high.Conversely, if the pressure that is relayed to the receiver isrelatively low, the pressure at which the air is discharged through thenozzle is likewise low. Under such circumstances, the eifect of theapper on the nozzle Varies with the pressure that is transmitted to thereceiver. 'Such variation causes a number of diiculties in an instrumentof this character which is intended to be highly accurate. Calibrationof the instrument becomes difcult due to the variable effects of theflapper on the nozzle. Stability of theinstrument is also hindered andin many instances, there is a tendency of the instrument to hunt astable condition.

It is one object of the present invention to provide an improved airtransmitter of this type wherein the pressure at which the air isdischarged through the nozzle is constant or substantially so throughoutthe entire range of pressure that is transmitted to the receiver. Withsuch an arrangement, the effect of the llapper upon its nozzle issubstantially constant or uniform regardlessof the magnitude of thetransmitted pressure. In this manner, calibration of the instrument israther easily accomplished due to the relatively uniform conditionsunder which the pilotis functioning. Greater stability can also besecured and hunting is largely, if not entirely, eliminated. The

construction also lends itself to the ease with which the instrument maybe adjusted in zeroing the system, it being understood that under zeroconditions in systems of this character there is` usually a small amountof pressure transmitted to the receiver. n

Another object of the invention is to provide an improved relay forreducing the supplied pressure and transmitting the reduced pressure tothe receiver `in direct accordance with the control of the pilot.

A further object of the: invention is to provide a novel construction ofpilot wherein operating conditions are sub- 2,718,896 Patented Sept. i27, 1955 ice stantially the same regardless of the pressure controlledby the pilot.

With the foregoing and other objects in View, which will be mademanifest in the following detailed description and specifically pointedout in the appended claims, reference is had to the accompanying drawingfor an illustrative embodiment of the invention, wherein the figure is avertical section through an air transmitter embodying the presentinvention.

Referring to the accompanying drawing wherein similar referencecharacters designate similar parts throughout, in an air transmitter ofthis general type the purpose of the construction is to receive airpressure from a supply source through a supply conduit 10 and to reducethis air pressure and deliver it, through an outlet conduit 11tin directproportion to the position assumed by a movable governing element 12.The situations under which an air transmitter of this type may be usedare innumerable but to facilitate a clear understanding of the presentinvention, a typical situation and typical values will be referred toherein as follows:

The air pressure that is supplied through the supply conduit 10may beassumed to be a constant or substantially constant pressure ofapproximately twenty pounds per square inch from any suitable source ofsupply. The pressure that is delivered through the outlet conduit 11 tothe receiver may be assumed to be three pounds per square inch when thereceiver is at zero. This pressure may run as high as twenty pounds persquare inch. The governing element 12 is shown as being mounted on arocker shaft 13 which is connected by means of adjustable linkage,generally indicated at 14 to a torque tube or the equivalent indicatedat 15. This torque tube may be turned in any suitable manner, such as bymeans of a differential pressure measuring device and the rotationalmovement of the torque tube is also transmitted by means of adjustablelinkage 16 to a rocker shaft 17 on which a pointer 18 is mounted. l l

Regardless of what` structure may actuate it, the governing element 12rises and falls in` direct accordance,

therewith, the end of the governing element swinging about the axis ofthe rocker shaft 13 as a center. It is the position of the governingelement 12 that controls or affects the pressure that is transmittedthrough the Aoutlet 11 to the receiver. In other words, if the end ofthe governing element 12 is caused to rise from the position shown bythe torque tube 15, the pressure transmitted through the outlet 11 islikewise caused to rise. Conversely, if the position of the governingelement 12 falls, thepressure that is transmitted through the outlet 11likewise falls directly in accordance therewith.

The transmitter embodying the present invention consists of a housingpreferably formed of several parts, one of which is a base 19 havingsuitable attaching lugs 20 Vby which the same may be mounted on apanelboard or equivalent structure by means of screws 21. The inletconduit 10 is drilled in this base and the outlet conduit 11 issimilarly formed therein. On the base there are two superposedcylindrical housing elements 22 and 23 between which there is disposed aspider 24. On the upper housing element 23 there is mounted a cap 25.These parts of the housing are suitably gasketed, such as by gaskets 26and cooperatively forma chamber 27 in the housing. The housing elements22, 23, the spider 24, the cap 25, and the base 19 are all rmly attachedtogether by bolts, not shown, which extend vertically through the wallsof the housing elements. The inlet conduit 10 leads into a radiallydrilled hole 28 in the base from which a branch conduit 29 leads to thespider 24 and to the cap 25. A restricter 30 is mounted in this Cbranchconduit, this restrictor being in the form of a to lthrottle down theinlet pressure that is received in the inlet conduit 10.

"'Withn the chamber 27 there is disposed the operative members of arelay. This relay consists of a pair of opposed external bellows 31 and32. Within each extern'al'b'ellows there are internal bellows 33 and34p. These bellows all have -their inner ends anchored or secured to theside faces of the spider 24. Their outer or free ends are anchored orare secured on caps 35 and 36, respeetivelyl Between the verticalapertures 37 that are formed in the spider 24 and which keep the upperportion fof the chamber `27 in constant communication with the lowervportion thereof there is a radial hole 3,8drilled in the spider whichprovides communication between the branch 'conduit 29 above therestricter 30 and the space or chamber 39 between the bellows 32 and 3 4located on the underside of the spider. In this manner, reduced pressurewhich is reduced by the restrictor 30 is constantly supplied to thechamber 39 between the lower bellows. This pressure is effective to urgethe lower bellows to expand downwardly.

The end caps 35 and 36, however, are caused to move in unison bymeans ofa rigid connector made up of parts 40'and 41 that are mutually threadedtogether as indicated at 42. These parts are movable through the spider24 andhave shouldersengageable with the spider to limit movements of thebellows under excessive or extreme conditions. The spider 24 has also aradial outlet hole 43 drilled therein between the apertures 37 which`communicate with the space around the connector made up of the parts 40and 41. In the lower part 41 there is formed a passage 44 in which thereis formed a valve seat 45 thatfis engageable with a valve closure 46 ona relay valve. This valve seat, when in its unseated position as shown,permits air pressure in the chamber 27 to escapethrough the passage 44and the hole 43 to atmosphere. However, when the valve seat 45 is seatedon the'closure egress from the chamber 27 through the outlet 43 isprevented. The closure 46 is on a stem 47 that extends through a valveseat 48 screwed into the top of the base 19 and which receives airpressure directly from the inlet conduit 10.

The stem 47 slidably extends through an acorn nut 49 which constitutes aclosure adapted to seat on the seat 4 8. The stem 47 is threaded into anacorn nut 50 so that adjustment of the closure 49 with respect to thestem 47 can be easily accomplished. The acorn n ut 50, provides aspringseat for a light compression spring 51 which is also seated on acap 5,2 screwed into the bottom of the basen19. As the closure46 isA ofsucha Size that o itjmay pass through the valve seat 48 adjustment ofthe closure 49 with respect to the stem is easily accomplished byunscrewing the cap 52, removing the spring 51, and allowing the entirerelay valve made up of the closure 46, stem 47, and acorn nuts 57,0 and49, to be removed. B y screwing the nut 50 up or down on the stem 47,adjustment is readily accomplished.

With the relay as above described, it will be appreciated that thebellows 31 and 32, which are opposed, are both subjected to whateverpressure exists in the chamber 2,7. If, for any reason, the pressure inthe chamber 39 causes the opposed bellows 31 and 32 to descend, thevalve seat 45 will engage the closure 46 and close the outlet 43 againstegress therethrough. If the pressure in the chamber 39 is sufcient tonot only seat the valve seat 4S against the closure 46 but to depressthe stem 47 and closure 49 against the spring pressureV at 5,1 and theair pressure supplied through the inlet 10, air pressure from the inletis permitted to enter the chamber 27 and be conducted therefrom to theoutlet 11. On theother hand ,if.the pressure in the chamber 27 is relatively high and the pressure in the chamber 39 is reduced, allowing thebellows to rise, the closure49 will seat, cutting off the supply ofcompressed air from theA inlet 10 and if the bellows continue to rise,the seat 45i 4 will disengage the closure 46 and allow egress from theChamber 27 thrgush the Quflet 43- lt will be noted that the outlet 43 isin communication with the chamber or Yspace between the bellows 33 and31 so that no air leak is formed therein. The bellows 33 in the presentconstruction performs no important function other than to form abalanced structure, it being of equal size and shape to the internalbellows 34. However, it is possible to utilize the space between thebellows 31 and 33 in adapting the construction to controllers. In arelay of this type, where the inlet pressure iny the inlet 10 is twentypounds per square inch, it is found that ordinarily onequarter pound persquare inch is required to unseat the closure 49 when the pressure inthe chamber 27 is ve pounds per square inch. In other words, if thepressure in the chamber 39 is just sufficient to cause the seat 45 toengage the closure 46 and thus close the outlet 43 against egresstherethrough, an additional onequarter pound per square inch is requiredto unseat the closure 49 and thus permit flow of compressed air from theinlet 10 into the chamber 27.

The pilot governing the action of the relay consists of two opposedbellows 55 and 56 mounted upon the upper and lower sides of the cap 25,respectively. These bellows have their caps rigidly connected by aconnector made up of the parts 57 and 58 which are threadedly connectedtogether and serve to support a washer 59 that is engageable with thecap to limit upward movement of the connector.

In` the upper part 57 a nozzle 60 is threadedly mounted so that it` maybe adjusted relatively thereto and this nozzle issealed against leakagethereabouts by means of an Ofring 61;; A- passage 62 formed in theconnector provides communicationy between the interiors of the two`bellows andthe nozzle. The bellows are urged or are biased in a downwarddirection by means of a plurality of tension` springs 63 which connectthe cap of the upper bellows with a spring retainer 64 that is heldagainst the underside of the cap 25. At the extreme upper end of thenozzle 6( )there is a small orifice 6 5, the size of which together withthe restraint of the ilapper 71 governs the working pressure that isAmaintained in the bellows 55 and 56. This working pressure is suppliedfrom the branchy conduit `29. through a radial bore-66 in the cap. Onthe nozzle ther-eis abracket, 67 that is held against an externalshoulder on the nozzle by means of a split dished washer 6,8, Thisbracket has upstanding ears 69 between which the stem 70 of a, apper 71is pivoted. The bracket671 is held against rotation relativeto thenozzle by means of a guide pin 721 that is mounted on the cap oftheupper.l bellows andwhichslidably extends intothe bracket. Thismaintains the stem 70 in alignment with thegovernilrlg element 1 2. Theweight of the ilapper 71 urges the dapper-down over the orifice of thenozzle. However, theVV extent towhich the flapper closes thel orifice isgoverned by the engagementfbetween vthe stem and the governing element12,- Undervnormal conditions. the apper is slightly spaced from thevend-of the nozzle in the neighborhood of .001" which is variabledepending upon the extent to which the stem 70 is engaged by thegoverning element 12v.

In thisjformof construction` of pilot it will be observed that thesprings 63-urgethe two bellows S5 and 56 downwardly. Thei workingpressure .that is maintained within the bellows has a neutral orbalanced effect inasmuch as both bellows are, of the same eifective areaor substantially so. However, the exterior of the. lower bellows 56being within the chamber 27 is subjected to the pressure in the chamberwhich is etfecti'veto,urgel both bellows upwardly against theactiono'flthe springs 63.

The operation ofjthe above described-construction is as follows;

In the position shown in the gure, the closure 46 has 5. been disengagedby the seat 45, opening the chamber 27 through the closure 46. Theclosure 49 is shown as being seated, cutting off the supply ofcompressed air from the inlet V to the chamber 27. The stem 70 isillustrated as being beneath and o ut of engagement with the governingelement 12. Consequently, the weight of the apper 71 is free to exertits maximum effort to close the orifice 65. The closing of the orifice65 causes the operating pressure delivered through `the restricter 30 tobuild up and the building up of this pressure is transmitted to thechamber 39. The increase of pressure in the chamber 39 causes theopposed bellows of the relay to descend, causing the seat to engage theclosure 46 and ultimately the stem 47. tofunseat the closure 49,admitting ,compressed air to the chamber27 from the inlet 10. As air isadmitted to the chamber 27 the pressure increases and the increase inpressure is effective on the bellows 56 tending to. elevate the opposedbellows 55 and 56 of the pilot. When these bellows move upwardly inunison, due to the rigid connectors 57 and 58, the nozzle 60 and `theflapper, together move upwardly until the stem 70 engagesthe governingelement 12. When thegoverning element 12 is engaged by the stem 70 thestem pivots on the ears 69 lifting theflapper 71 from the nozzle andallowing air to escape through the orice more readily.y However, as` theapper is mounted on the nozzle and is movable therewith in all positionsthe relationship of the apper with` respect to the nozzle ,remainssubstantially the same except for the slight change in position involvedin `opening and closing the nozzle. This arrangement is conducive toconsistency of operation in all positions. The opening of the orifice 65by-the apper allows a reduction in pressure to take place within thebellows 55 and 56. This reduction in pressure causes the pressure withinthe chamber 39 to be correspondingly reduced, and as previouslyexplained, a reduction in pressure in this chamber allows the bellows ofthe relay to tend to return to their normal or neutral position whereinthe closure 49 is seated and the closure 46 is also seated. The pressurewithin the chamber 27 which is transmitted through the outlet 11 to thereceiver is consequently commensurate with the position of the governingelement 12. It will, of course, be appreciated that whatever pressureexists in the chamber 27 is effective on the bellows 56, causing thebellows of the pilot to quickly assume a stable ycondition wherein theflapper 71 is so spaced from the end of the nozzle that a small amountof air is continually escaping. In such position the orifice 65 isneither fully closed nor fully open.

If conditions change so as to change the position of the torque tube 15and elevate the governing element 12, the weight of the ilapper 71 againtends to close the orifice 65, bringing about an increase of pressure inthe bellows 55 and 56 and an increase in pressure in the chamber 39.This increase in pressure in the chamber 39 may be effective to admitmore `air to the chamber 27 from the inlet 10 as previously explained,with the result that the same operation is to take place as previouslyexplained until the stem reengages the governing element 12, causing theflapper to open the orifice 65.

On the other hand, if the torque tube 15 should be so actuated as todepress or lower the governing element 12, this depresses the stem 70,lifting the apper 71 and thus opening the orifice 65. The opening of theorifice 65 to a wider or greater extent allows air to escape through thenozzle more readily. This causes a reduction in pressure within thebellows 55 and 56 which reduction is .transmitted to the chamber 39.When the pressure in the chamber 39 is reduced the bellows of the relaytend to rise into their normal position, causing the seat 45 todisengage the closure 46 and allow some of the pressure in the chamber27 to be released through the outlet 43. A release of the pressure inthe chamber 27 reduces nthe pressure that is transmitted to the receiverthrough the outlet 11. It is also effective tp reduce the Cit forceacting on the lower bello"s $6 and 'permit-the springs 63 to lower bothbellows of the pilot. 3As the upper bellows is lowered the nozzle andthe apper are also lowered until the stem 70 i`s` just about todisengage the governing element 12. When this occurs the apper 7lreturns to its normal position only slightly spaced from the end of thenozzle and a new set of conditions in equilibrium is quickly obtained.

It will be appreciated that with this type of arrangement the pressurewithin the bellows 55 and 56 of the pilot and within the chamber 39 issubstantially a constant. The only sensible variation that is requiredin the pres'- sure is that pressure that is necessary to unseat theclosure 49 after lthe closure 46 has been seated on the seat 45. At aworking pressure of five pounds per square inch this excess of pressurerequired to unseat the closure 49 need only be about one-quarter poundper square inch. Conf sequently, under any set of conditions thevariation in the operating pressure discharged through the orifice 65and tending to lift the apper 71 is substantially the same, thevariation being only about one-quarter pound per square inch. This istrue regardless of what the pressure may be in the chamber 27 that istransmitted through the outlet 11 to the receiver. Consequently,calibrationwith ref spect to the scale traversed by the pointer 18 isgreatly facilitated. An also greater stability can be secured andvariations due to hunting are avoided. The arrangement is such thatzeroing of the instrument can be easily accomplished. Thus, if a certainposition of the governing element 12 corresponds to a zero position ofthe pointer 18, and in such position it is desired that the pressure inthe outlet 11 be three pounds per square inchit is possible to easilyadjust the nozzle andthe apper by merely screwing the nozzle 60 up ordown with respect to the part 57 until conditions are such that theflapper will be opened the required distance to cause a three poundpressure to be delivered through the outlet 11 while the governingelement 12 is in the position stated.

From the above-described construction it will be appreciated that theimproved air transmitter has a number of advantages not only in ease ofcalibration, ease of adjustment, accurate transmission of pressure tothe outlet 11, but also in the ease of manufacture, assembly, andmaintenance.

The mounting of the pilot bleed nozzle 60 and the positioning of thesensing flapper 71 on one end of a pair of opposed bellows whosefloating ends are rigidly connected; the feeding of the air to thenozzle through the interior of the bellows and the positioning of theentire pilot assembly such that transmitted air pressure in the chamber27 is effective on the exterior of the bellows 56, produces aconstruction having a constant sensitivity at all positions regardlessof any stabilized output pressure. The use of opposed bellows whosefloating or free ends are rigidly connected in the relay valve togetherwith the porting with relation thereto as illustrated is such that thetransmitted air pressure has no effect upon them as to their position.Their position is controlled or determined solely by the pilot nozzlepressure which is determined by the position of the flapper 71 withrespect thereto. Other advantages of the present construction will beappreciated by those skilled in the art.

Various changes may be made in the details of construction withoutdeparting from the spirit and scope of f the invention as defined by theappended claims.

I claim:

l. An air transmitter comprising a housing providing a chamber, a spiderin said chamber, a pair of opposed bellows in the chamber mounted uponthe spider, means connecting the outer ends of the bellows to cause themto move in unison, a second pair of opposed bellows mounted on a wall ofthe housing, one of the second bellows being disposed in said chamber,means connecting the outer ends of the bellows of the second pair tocause them to move in unison, a nozzle mounted on the outside bellows ofthe second pair and connected to the interiors there` apper engageablewithv the nozzle to control egress therefrom pivotally supported o nthesecond pair of bellows so` as to be movable therewith, means foractuating the apper relatively to the nozzle,` a supply conduit leadingto the housing, a restricter in a branch of said conduit leadingA to theinteriors of both sets of bellows, there being an inlet from the supplyconduit leading, into said chamber, there being two outlets from saidchamber and a relay valve controlling the inlet and one of the outlets.

` 2'. An airl transmitter comprising a housing providing a chambenjaspider in said chamber, a pair of opposed bellows in the chamber.mounted upon the spider, means connecting the outer ends of the bellowsto cause them to move in unison, a second pair of opposed bellowsmountedjonawall ofthe housing, one of the second bellows being disposedin said chamber, means connecting the outer ends of the bellows of thesecond pair to cause them to move in unison, a nozzle mounted on theoutside bellows of the second pair and' connected to the interiorsthereof so as to receive fluid therefrom, spring means biasing thebellowsofthe second pair towardsv said chamber, a apper engageable withthe nozzle to control egress therefrom pivotally supported, on thesecond pair of bellows so as to be movable therewith, means foractuating the 'dapper relatively to the nozzle, a supply conduit leadingto the housing, a restricter in a branch of said conduit leading to vtheinteriors of both sets ofbellows, there being an inlet from the supplyconduit leading into said chamber, there being an outlet through awallof the chamber, a second outlet through the connecting means of therstmentionedpair ofI bellows and through the spider, and a relayvalvecontrolling the inlet and the outlet through CII the Connectingmeans of vthe rstfmentoned4 pair of bellows.

3. An, air transmitter comprising a' housingprovidinga chamber,v aAvspider in said chamber, apain of opposed'` bellows in, the chambermounted, u pon the Spidenmeans. connecting the outer ends o the, bellowsto,cause ,themtof move in,unisoniajseeondjpair of opposed bellowsl'rlolllledl on a wall of thehousing, one of the,secondfbelloyvsibeingldisposed in` said,` chamber, means connecting Ithe outer ends of thebellows of the second pair to cause them; to,-

move in unison, a, nozzle adjustably mountedon the loutside bellows ofthe second pair` and'connected tothe interiors thereof so as to receive`Huid therefrom, spring` means biasing the bellows of the second pairtowards saidl chamber, a flapper engageable with the nozzle; to controlegress therefrom pivotally supported on the second pair of bellows sovas to be movable therewith, means, for actuating the apper relativelytothe nozzle, a supply conduitleadingto the housing, a restricter in abranch of said conduit leading to the interiors of both sets, ofbellowsther.e being an inlet from the supply conduit leading into saidchamber, there being two outlets from said chamber, and a relay valvecontrolling the inlet andone of the outlets.,

References Cited in the le of this patent UNITEDy STATES PATENTS

